The present invention relates to electronic communications on a network and an effective method for isolating, and more specifically diagnosing system problems.
A typical collision-detection network, such as an ethernet local-area network (LAN), comprises a computer system or Data Terminal Equipment (DTE) which is attached to a transceiver or Medium Access Unit (MAU) via an Attachment Unit Interface (AUI) and transceiver cable. The MAU is attached to an ethernet coaxial cable bus.
Communication failures in any network may be the result of problems in the attached computer systems, problems with the system's attachment to the bus (transceiver and transceiver cable), or problems with the bus itself. Often errors which are diagnosed as computing system errors are the result of problems within the network or network connections. Excessive time and money have been spent in the resolution of such problems.
In many types of networks, merely disconnecting the DTE from the bus and routing the outgoing DTE data back to its own input data can determine whether or not the failure lies in the DTE. Such conventional "wrap test" methods have been used with collision-detection networks such as ethernet to diagnose a DTE by checking data transmission along the differential outbound and inbound data lines (DO+/DO- and DI+/DI-). A wrap device is attached to the AUI interface to test normal transmit and receive operations of DTE. However, this type of diagnostic test is incomplete. In order to fully isolate and verify the ethernet operation of the computer system, additional testing is needed.
A diagnostic test should verify all commonly used ethernet functions, instead of only transmit and receive operations. Again using ethernet as a paradigm, such functions may also include verification of: collision detection along the inbound control lines (CI+/CI-), continuity on the outbound control lines (CO+/CO-), and the power provided by DTE (VP and Vc). Conventional wrap testers do not test these functions, and thus do not realize the cost savings attributable to more comprehensive network testing.